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Zyxel security advisory for dnsmasq vulnerabilities

Zyxel is aware of the recently disclosed vulnerabilities of dnsmasq, as identified in US-CERT vulnerability note VU#973527 with vulnerability IDs CVE-2017-14491 through CVE-2017-14496 and CVE-2017-13704, as listed in table 1.


What are the vulnerabilities?

Dnsmasq is a piece of open-source software widely used in Android, Linux and a variety of networking equipment operating systems. The vulnerabilities are present in dnsmasq version 2.77 and earlier; version 2.78 of dnsmasq has been released to address these vulnerabilities.


Table 1

CVE Issue Vector
CVE-2017-14491 Heap-based Buffer Overflow DNS
CVE-2017-14492 Heap-based Buffer Overflow DHCP
CVE-2017-14493 Stack-based Buffer Overflow DHCP
CVE-2017-14494 Information Exposure DHCP
CVE-2017-14495 Uncontrolled Resource Consumption
(resource exhaustion)
DNS
CVE-2017-14496 Integer Underflow DNS
CVE-2017-13704 Integer Underflow DNS

Please see: https://security.googleblog.com/2017/10/behind-masq-yet-more-dns-and-dhcp.html for more technical information.


How are Zyxel resolving the vulnerabilities?

At Zyxel we treat security as a top priority and we have conducted a thorough investigation and identified a list of vulnerable products within their warranty and support period, as shown in table 2 below. For products not listed, they are not affected because they do not make use of dnsmasq.

We are now deploying or backporting the latest version of dnsmasq (version 2.78) into the vulnerable products.

Please refer to table 2 for the detailed release schedule. The patch firmware will be available for download at Zyxel Support Center .


Table 2

Product Series/Model Patch firmware versionAvailability
DSL CPE AMG1302-T11C ABCG12C0 Feb 2018
VMG1312-B10A AAJZ14C0 Jan 2018
VMG1312-B10D V5.13(AAXA.7) Dec 2017
VMG1312-B30A AATO9C0 Jan 2018
VMG3312-T series ABFX1C0 Dec 2017
VMG3625-T series ABIE1C0 Oct 2017
VMG3925-B10B AAVF10C0 Dec 2017
VMG3926-B10A AAVF10C0 Dec 2017
VMG5313-B10B V5.13(AAYY.6) Dec 2017
VMG8823-B10B V5.13(ABEJ.2) Dec 2017
VMG8823-B30B V5.13(ABEJ.2) Dec 2017
VMG8823-B50B V5.13(ABEJ.2) Dec 2017
VMG8823-B60B V5.13(ABEJ.2) Dec 2017
VMG8924-B10A
VMG8324-B10A
AAKL20C0 Jan 2018
VMG8924-B10D V5.13(ABGQ.1) Dec 2017
VMG8924-B30A AAPQ14C0 Jan 2018
VMG8924-B30D V5.13(ABGP.1) Jan 2018
XMG3512-B series ABDR1C0 Dec 2017
DSL CPE (Gemini) Gateway 400 6.38.2.10.03 13-Oct 2017
Speedlink 5501/6501 4.38.2.10.06 13-Oct 2017
Speedlink 5502 7.39.2.01.00 27-Oct 2017
VMG5304 8.39.3 27-Oct 2017
VMG8029 10.39.3 20-Oct 2017
VMG8546 9.39.3 20-Oct 2017
Ethernet gateway EMG2306 V1.00(AAJM.5)C0 Dec 2017
EMG2926 V1.00(AAVK.6)C0 Oct 2017
EMG3425 V1.00(AAYJ.11)C0 Dec 2017
GPON ONT PMG5317-T20A V521ABCI4C0 30-Nov 2017
PMG5317-T20B V540ABKI1C0 30-Nov 2017
Home router NBG6515 V1.00(AXS.5)C0 Feb 2018
NBG6604 V1.00(ABIR.2)C0 Jan 2018
NBG6617 V1.00(ABCT.6)C0 Dec 2017
NBG6815 V1.00(ABBP.7)C0 Feb 2018
NBG6816 V1.00(AAWB.10)C0 Dec 2017
NBG6817 V1.00(ABCS.8)C0 Jan 2018
LTE CPE LTE4506-M606 V1.00(ABDO.3)C0 15-Dec 2017
LTE7410 V2.60(ABAW.6)C0 Feb 2018
LTE7460 V1.00(ABFR.4)C0 20-Dec 2017
WAH7706 V1.00(ABBC.8)C0 22-Dec 2017
WiFi system WSQ50 V1.00(ABKJ.2)C0 10-Nov 2017
Wireless extender WAP6806 V1.00(ABAL.6)C0 18-Feb 2018

What should I do now to protect against the vulnerabilities?

The following short-term mitigations could be put in place to remove or reduce the threat:

  • For ISP customers, ISP’s DNS server filters all DNS responses to check for the malicious code
  • Zyxel CPE is reconfigured so that it does not act as the DNS server for LAN side DHCP clients by issuing the DNS servers as “obtained from ISP” or DNS static IPs. Note this mitigation is only applicable to VDSL and LTE models.

For more information and technical details regarding the vulnerabilities please see below references:

  1. US-CERT VU note: https://www.kb.cert.org/vuls/id/973527
  2. Disclosure by Google: https://security.googleblog.com/2017/10/behind-masq-yet-more-dns-and-dhcp.html

Please contact your local service representatives if you require further information or assistance. To report a vulnerability, please contact security@zyxel.com.tw